Projection exposure apparatus for semiconductor lithography are e.g. described in US 2007/0248127 A1, US 2007/0096566 A1, US 2007/0114655 A1, US 2004/0079898 A1, US 2005/0094118 A1 and US 2005/190351 A1. In general the actuator system can be embodied as a damping system for reducing mechanical vibrations. In this case, the mechanical vibrations discussed generally lead to impairments of the optical imaging quality, which are manifested for example as a loss of contrast and impair the yield of semiconductor products having entirely satisfactory quality. During the operation of actuator systems, it is practically unavoidable that heat is released. The heat can for example originate from electronic components of the actuator system such as amplifiers, for example, or else be produced by mechanical components of the actuator system as an undesirable secondary effect. The occurrence of heat in the system and in particular the occurrence of thermal gradients, can have a disadvantageous effect on the system; thus, in the case of a projection exposure apparatus, it can likewise result in an impairment of the optical imaging quality.